Fluorinated thermoset polyurethane elastomers prepared from polyether coprepolymers formed from mono-substituted fluorinated oxetane monomers and tetrahydrofuran

Abstract

This application is directed to novel fluorinated polymers and prepolymers derived from mono-substituted oxetane monomers having fluorinated alkoxymethylene side-chains and the method of making these compositions. The mono-substituted fluorinated oxetane monomers having fluorinated alkoxymethylene side-chains are prepared in high yield by the reaction of a fluorinated alkoxides with either 3-halomethyl-3-methyloxetane premonomers or aryl sulfonate derivative of 3-hydroxymethyl-3-methyloxetane premonomers. Preparation of a mono-substituted 3-bromomethyl-3-methyloxetane premonomer via a simple, high yield process amenable to commercial scaleup is also disclosed. The fluorinated oxetane monomers of this invention can be readily homo/co-polymerized in the presence of a Lewis acid and polyhydroxy compounds to obtain hydroxy-terminated polyether prepolymers having fluorinated alkoxymethylene side chains. Additionally, the fluorinated oxetane monomers can be copolymerized with non-fluorinated monomers such as tetrahydrofuran to give polyether prepolymers with improved hydrocarbon compatibility. These prepolymers are polydisperse and exhibit number average molecular weights from 5,000 to about 50,000. These prepolymers are amorphous oils with primary hydroxy end-groups and thus function efficiently as the soft block for the synthesis of a variety of thermoset/thermoplastic elastomers and plastics having the characteristics of very low surface energy, high hydrophobicity, low glasss transition temperature and low coefficient of friction. The polyurethanes derived from the prepolymers of this invention are elastomeric and, in addition to the above characteristics, exhibit high moisture resistance, high tear strength and excellent adhesion to a variety of substrates.

What is claimed is: 
     
       1. A fluorinated thermoset polyurethane elastomer having random FOX/THF segments and having the structure, ##STR14## where: a) n is 1-3; b) R is selected from the group consisting of methyl and ethyl;   c) R f  is selected from the group consisting of linear and branched perfluorinated alkyls having 1-20 carbons, and oxaperfluorinated polyethers having from about 4-20 carbons;   d) R 1  is a divalent hydrocarbyl radical;   e) X is 1-20;   f) Y is 10-150;   g) Z is 2-50.   
     
     
       2. A fluorinated thermoset polyurethane elastomer as in claim 1 wherein said isocyanate segments are selected from the group consisting of hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 4,4'-methylene diphenylisocyanate (MDI), polymeric MDI, toluene diisocyanates, hydrogenated MDI (HMDI), polymeric HDI, trimethylhexane diisocyanate and mixtures thereof. 
     
     
       3. A fluorinated thermoset polyurethane elastomer as in claim 2 wherein said fluorinated polyether segment is produced from at least one monomer selected from the group consisting of 3-(2,2,3,3,4,4,5-heptafluorobutoxymethyl)-3-methyloxetane, 3-(2,2,2-trifluoroethoxymethyl)-3-methyloxetane, 3-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyloxymethyl)-3-methyloxetane, 3-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorooctyloxymethyl(-3-methyloxetane, and 3-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heneicosafluorododecyloxymethyl)-3-methyloxetane.